Most people go to church for forgiveness, what the new hope church members got was truly unforgivable, a betrayal in their midst, with nearly all ten commandments broken. Including thou shall not kill. What would catch the killer was a love letter left in a trash can torn to pieces but not nearly enough. Tonight right here you'll see for yourself those interrogation tapes, that helped break this case. Here is jim avila. Reporter: Independence, missouri, stick a pin in the middle of an american map. And this is what you get. Bible country. Home of harry truman, where a love of god, country and guns meet. And on this day, independence is saying good-bye to a man who personified all that middle america is about. Family man and former marine. 42-year-old randy stone, pillar of the community and now murder victim. He was a fun loving person, he was one of these people that no matter what he was doing he, he was making the best of it, and it was constant jokes and, randy was just a fun, infectious person to be around. Reporter: Hundreds turn up for the funeral listening to randy's pastor, best friend and spiritual advisor david love who gives a stirring, heart-felt eulogy. We sit here today and we weep not just because of the separation of our loved one but because of the questions that death brings. Questions like why, "why him?" "Why now?" Delivered a powerful eulogy. It was a very warm and comforting thought that he was in heaven that he was in glory. Without answers, death seems so cold. Reporter: But mourners weren't the only ones in attendance. Detectives were there too, recording in the church that day. Because they believed the killer might be attending the funeral. It was, after all, only days earlier that randy's wife, teresa, stumbled upon a horrific scene. A murder mystery. It was the middle of the day. She stopped by the insurance company she ran with her husband. As she pulled up, she noticed things just did not look right. The shades were drawn during business hours, and the doors locked. She came into the office and then found him laying in her office, on the floor, kind of behind her desk, and he was laying on his side, and, was bleeding. She stepped over the body, and placed the phone headset on, and then proceeded to call her parents. And told them that randy had been shot, and they said, then call 911. 911, do you need police, fire or medical? Yesi do please. Okay, take a breath. Where are you at? I -- I just walked into my office and my, my husband's lying on my floor in my office. Okay now, what's wrong with your husband? He's, he's been, I don't know. There's blood everywhere. It's coming out of his ear. The police got to the scene, she ran out the door, collapsed in the yard. Reporter: Theresa not only had she lost her husband of 19 years, the father of her two children, but the man she had known since childhood says randy's mom, clara. So how did he meet teresa? We's on the same block, they kind of grew up on the same block, so he'd known her for years. Reporter: At 18 randy enlisted in the marine corps and lost touch. But when he returned to independence, their relationship reignited. He gets out of the marines, it becomes more serious. Yeah. One day he come in and said, we're getting married, they had a nice wedding out at new hope Reporter: Just like that -- soon they had a son and a few years later a daughter. A picture perfect family, in a picture perfect american town. You know, he's a, you know, former marine, tough guy, but his devotion to his wife was -- was really something to behold. He wrote poetry to her. And his marriage was -- was -- was the center of his life -- was the center of his life. Reporter: And the glue that kept them together -- their church. New hope baptist where they were married and had their children baptized. Drove church buses, advised them on financial matters, taught sunday school classes. Teresa was -- helping in the kitchen to singing in the choir, she was always there. Randy was, was there every sunday, wednesday night, and if there was an activity, he was there. He really fed on the spiritual nourishment that that church offered. Reporter: With family, faith and a tight knit circle of friends it seemed randy and teresa were leading a righteous, pure, even devout life. He told me he would love her until the day he died, and believe me, he did. Reporter: But, now the 42-year-old insurance salesman, with no known enemies lay dead in a pool of blood. A single bullet wound to the head. Police began to comb the crime scene. And more than $150 dollars still sat on the desk. His wallet never moved from his pocket. So what did this tell you about whether or not this could be a, a burglary gone bad or, robbery or, or just this random stranger? This looked exactly what it turned out to be, like an execution. Somebody that he knew and trusted, and shot him at the point his back was turned. Reporter: The murder took only one shot. Investigators find the single .40 caliber bullet casing on the floor and another intriguing piece of evidence that would turn the case within the first hour in a nearby wastebasket. One of our people went through a, a trash, a trash canister next to teresa stone's office desk, and there was a, a one-page letter that had been torn up in multiple pieces. What it amounted to is some type of a, like a happy birthday or a love letter. Reporter: Happy birthday love. I am not in control of things yet, but when we are fully together your birthday will always be exciting. Anyone's attempt to shred it was pretty pathetic. It was ripped into nine squares, and placed in the trash can, um, on the day that randy happens to be murdered, in the same room. Reporter: I adore you I am blessed by you I need you. For savvy veteran police detective keith rosewaren, this wasn't adding up. How did you -- did you determine at the scene that this was not randy's love letter to his wife? There were some handwriting samples on randy's desk. The handwriting and penmanship really didn't look the same. Reporter: Suddenly, a love note gives police their first clue in the mystery of "who done it?" The first possible reason into why this god fearing, beloved pillar of the community would be struck down. The church closed ranks around teresa consoling and comforting, even her husband's eulogist, pastor david love, rushed to her side. David called and told me. And he said, "are you sitting down? Randy's been shot and killed." I drove straight to the office. And then I was fighting the police, I wanted to go in and see my baby and they wouldn't let me. Reporter: Police take theresa down to headquarters for questioning -- but even before she gets there, her behavior begins to raise eyebrows. They put teresa in the patrol car, and they drive her off, and almost instantly, she tells them, she's all out of tears, and she doesn't know if they're going to think that's strange, but she's all cried out. Anst -- instantly, is, has recovered.

This transcript has been automatically generated and may not be 100% accurate.

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{"id":20403812,"title":"Former Marine's Death Arouses Police Suspicions","duration":"7:28","description":"Act 1: With cash left behind, Randy Stone's death may have been a homicide.","url":"/2020/video/marines-death-arouses-police-suspicions-20403812","section":"2020","mediaType":"Default"}